A cordless communication system, such as a telephone system capable of performing wireless communication between a base unit and a handset, is well known in the art. One such cordless communication system is a cordless telephone system employing digital modulation described in Japanese patent application publication No. 6-338838. This digital modulation cordless telephone system includes a base unit and a handset, both of which are configured to return to a standby state after communication between the base unit and handset ends. After the base unit and the handset return to the standby state, the base unit periodically transmits data to the handset, and the handset periodically receives the transmitted data. The handset also transmits response data to the base unit upon receiving data from the base unit. Hence, the cordless telephone system disclosed in Japanese patent application publication No. 6-338838 periodically exchanges data between the base unit and the handset.
The digital modulation cordless telephone system described above generally employs frequency-hopping spread spectrum, periodically changing the frequency at which signals are exchanged between the base unit and the handset. Therefore, the base unit and the handset must periodically exchange data in order to always maintain the same frequency for communications. By periodically exchanging data between the base unit and handset, as described above, when the base unit detects an incoming call on a public line and transmits incoming call data to the handset, the handset can instantaneously receive the transmitted call data.